The basic idea is to use a pixel’s neighboring colors as
context to predict its own color. Up to 4 neighbors are
considered here: left, left-above, above, right-above.
To reduce the number of contexts, the combination of any
4 (or less) colors are mapped to a reduced number of
patterns. For example, 1111, 2222, 3333, … , can be mapped
to the same pattern: AAAA. SImilarly, 1122, 1133, 2233, …,
can be mapped to the pattern AABB. In this way, the total
number of color contexts is reduced to 16.
This almost doubles the gain of palette coding on screen
content videos.
on screen_content
--enable-palette +14.2%
--enable-palette --enable-tx-skip +21.2%
on derflr
--enable-palette +0.12%
with all other experiments +6.16%
Change-Id: I560306dae216f2ac11a9214968c2ad2319fa1718
Also make changes to transmit palette-enabled flag using
neighbor blocks as context.
on screen_content
--enable-palette +7.35%
on derflr
with all other experiments +6.05%
Change-Id: Id6c2f726d21913d54a3f86ecfea474a4044c27f6
on screen_content
--enable-palette +6.74%
on derflr
with all other experiments +6.02%
(--enable-supertx --enable-copy-mode
--enable-ext-tx --enable-filterintra
--enable-tx64x64 --enable-tx-skip
--enable-interintra --enable-wedge-partition
--enable-compound-modes --enable-new-quant
--enable-palette)
Change-Id: Ib85049b4c3fcf52bf95efbc9d6aecf53d53ca1a3
For 444 videos, a single palette of 3-d colors is
generated for YUV. For 420 videos, there may be two
palettes, one for Y, and the other for UV.
Also fixed a bug when palette and tx-skip are both on.
on derflr
--enable-palette +0.00%
with all experiments +5.87% (was +5.93%)
on screen_content
--enable-palette +6.00%
--enable-palette --enable-tx_skip +15.3%
on screen_content 444 version
--enable-palette +6.76%
--enable-palette --enable-tx_skip +19.5%
Change-Id: I7287090aecc90eebcd4335d132a8c2c3895dfdd4
Added palette coding option for Y channel only, key frame only.
Palette colors are obtained with k-means clustering algorithm.
Run-length coding is used to compress the color indices.
On screen_content:
--enable-palette + 5.75%
--enable-palette --enable-tx_skip +15.04% (was 13.3%)
On derflr:
--enable-palette - 0.03%
with all the other expriments + 5.95% (was 5.98%)
Change-Id: I6d1cf45c889be764d14083170fdf14a424bd31b5
Also fixes some build issues with certain experimental combinations.
Results on derflr with all experiments on: +5.516%
Change-Id: I9b492f3d3556bd1f057005571dc9bee63167dd95
Initial patch to remove get_zbin_mode_boost() and
cpi->zbin_mode_boost.
For now sets a dummy value of 0 for zbin extra pending
a further clean up patch.
Change-Id: I64a1e1eca2d39baa8ffb0871b515a0be05c9a6af
(cherry picked from commit 60e9b731cf8945403dbcf149a0f6dc745e5cabe1)
COMPOUND_MODES experiment encodes separate MV modes for each frame in a compound
reference prediction. Added modes NEAREST_NEARESTMV, ZERO_ZEROMV,
NEW_NEWMV, NEAREST_NEARMV, NEAR_NEARESTMV, NEW_NEARESTMV, NEAR_NEWMV,
NEW_NEARMV, and NEAREST_NEWMV.
Also enhances the wedge-partition expt to work better with compound
modes.
Results:
derflr +0.227
All experiments on: derflr +5.218
Change-Id: I719e8a34826bf1f1fe3988dac5733a845a89ef2b
Implements vertical, horizontal, and tm dpcm intra prediction for
blocks in tx_skip mode. Typical coding gain on screen content video
is 2%~5%.
Change-Id: Idd5bd84ac59daa586ec0cd724680cef695981651
A smooth weighting scheme is used to put more weight
on the intra predictor samples near the left/top boundaries
and decaying it to favor the inter predictor samples more as
we move away from these boundaries in the direction of
prediction.
Results:
derflr: +0.609% with only this experiment
derflr: +3.901% with all experiments
Change-Id: Ic9dbe599ad6162fb05900059cbd6fc88b203a09c
Disable SUPERTX mode when lossless mode is enabled because the largest
lossless transform size is 4X4.
Change-Id: I4167959a282728d62354119ced99ca29febabfd1
In lossless coding, tx_size can be larger than 4x4 when transform
skipping is activated. Compared to regular vp9 lossless coding,
performance improvement for derf is about 5%; gain is larger
for screen content videos.
Change-Id: Ib20ece7e117f29fb91543612757302a2400110b4
This patch improves the non-transform coding mode. At this
point, the coding gain on screen content videos is about
12% for lossless, an 15% for lossy case.
1. Encode tx_skip flags with context. Y tx_skip flag context is
whether the prediction mode is inter or intra. UV flag context
is Y flag.
2. Transform skipping is less helpful when the Q-index is high.
So it is enabled only when the Q-index is smaller than a
threshold. Currently the threshold is set as 255 for intra blocks,
and 0 for inter blocks.
3. The shift of the prediction residue, when copying them to the
coeff buffer, is set as 3 when the Q-index is larger than a
threshold (currently set as 0), and 2 otherwise.
Change-Id: I372973c7518cf385f6e542b22d0f803016e693b0
Reimplements the supertx experiment from the playground branch.
Makes it work with other experiments.
Results:
With --enable-superttx
derflr: +0.958
With --enable-supertx --enable-ext-tx
derflr: +2.25%
With --enable-supertx --enable-ext-tx --enable-filterintra
derflr: +2.73%
Change-Id: I5012418ef2556bf2758146d90c4e2fb8a14610c7
Extends the ext-tx experiment to include regular and flipped
DST variants. A total of 9 transforms are thus possible for
each inter block with transform size <= 16x16.
In this patch currently only the four ADST_ADST variants
(flipped or non-flipped in both dimensions) are enabled
for inter blocks.
The gain with the ext-tx experiment grows to +1.12 on derflr.
Further experiments are underway.
Change-Id: Ia2ed19a334face6135b064748f727fdc9db278ec
Preliminary 64x64 transform implementation.
Includes all code changes.
All mismatches resolved.
Coding results for derf and stdhd are within noise. stdhd is slightly
higher, derf is slightly lower.
To be further refined.
Change-Id: I091c183f62b156d23ed6f648202eb96c82e69b4b
This commit refactors the rate distortion structure used in the
non-RD coding mode and saves a few RDCOST calculations.
Change-Id: I62c3416c300d2c5372f21b96d93a6b633a34ab3a
Its functionality has been replaced with choose_partitioning and
threshold based control on split mode check.
Change-Id: Ic9bb321df06b524f5c38ea5874dc6f6a8f93c5e3
This speed feature has been deprecated in both yt and rtc coding
modes. This commit removes the related operations.
Change-Id: I079c79c6adafe45581af2ebf8b98faebcface1ce
This commit re-designs the recursive partition search scheme in
rtc speed -5. It first checks if the current block is under cyclic
refresh mode. If so, apply recursive partition search. Otherwise,
perform sub-sampled pixel based partition selection. When the
pre-selection finds the partition size should be 32x32 or above,
use the partition size directly. Otherwise, apply partition search
at nearby levels around the preset partition size.
It is enabled in speed -5. The compression performance of rtc
speed -5 is improved by 9.4%. Speed wise, the run-time goes slower
from 1% to 10%.
nik_720p, 1000 kbps
33220 b/f, 38.977 dB, 10109 ms -> 33200 b/f, 39.119 dB, 10210 ms
vidyo1_720p, 1000 kbps
16536 b/f, 40.495 dB, 10119 ms -> 16536 b/f, 40.827 dB, 11287 ms
Change-Id: I65adba352e3adc03bae50854ddaea1b421653c6c
